Copolymer-type pigment dispersing agents have been developed in a variety of fields.
In the field of, for example, color liquid crystal displays, a copolymer-type pigment dispersing agent is used as a dispersing agent for a pigment to be contained in a radiosensitive composition used for forming a color layer. In this field, because of increasing demands for higher visible light transmittance and higher contrast, pigment particles are made further finer at least to a wavelength of visible light or smaller.
As a dispersing agent for stably dispersing such a pigment in the form of finer particles, various copolymers have been proposed. For example, Patent Document 1 and Patent Document 2 propose, for improving dispersion stability of a pigment, use of a dispersing agent composed of a block having a quaternary ammonium base and a block having no quaternary ammonium base.
Furthermore, Patent Document 3 proposes a radiosensitive composition used for forming a color layer, containing, as a dispersing agent, a copolymer having a repeating unit represented by formula (1), a repeating unit represented by formula (2) and a repeating unit represented by formula (3).
